carding,operating zones,operating principle and processes involved in making a carded sliver

1. “The Heart of Spinning”
4/12/2017 The Card

2. The Card
 ‘The card is the heart of the spinning mill’ and
 ‘Well carded is half spun’
 According to Dr. Artzt of the Research Institute in
Denkendorf, Germany, the operation of the card
shows:
 • the highest correlation to quality;
 • and also to productivity.
 The higher the performance, the more sensitive the
carding operation becomes
 and the greater the danger of a negative influence on
quality.

3. Varying types of design
Basic considerations
 Carding engines are basically designed for
processing either relatively long fibers (wool cards
with carding rollers) or relatively short fibers such as
those found in the usual short staple spinning mill.
Since machines of the latter type have flats
circulating on an endless path, they are referred to
as revolving flat cards.
 The name card is derived from the Latin ‘carduus’,
meaning thistle, the spiked fruit of which was used
in earlier times for plucking fibers apart.
 The working width was usually 1000 mm or 40
inches;
 Rieter recently increased it to 1500 mm on its new C

4. Introduction

5. History
 Since, 1965 production rates have increased from
about 5 kg/h to about 220 kg/h – a rate of increase
not matched by any other textile machine except the
draw frame.
 nowadays cards and blowroom form an integral,
homogeneous, inseparable unit, coordinated to
complement one another.

6. (1) The tasks of the card
 Opening into individual fibers.
 This is essential to enable impurities to be
eliminated and the other operations to be
performed.
 Elimination of impurities.
 The degree of cleaning achieved by the modern
card is very high, in the range of 80 - 95 %.
 Thus, the overall degree of cleaning achieved by
the blowroom and the carding room together is as
high as 95 - 99 %.
 But carded sliver still contains 0.05 - 0.3 % of
foreign matter.

7.  Elimination of dust.
 the card also removes a large proportion of the micro
particles that are bound to the fibers.
 Significant fiber/metal or fiber/fiber friction is
needed in order to loosen such particles. Both are
available on the card to a considerable degree, i.e. the
card is a good dust removing machine.
 Disentangling neps.
 It is often falsely assumed that neps are eliminated at
the card; in fact, they are mostly opened out. Only a
fraction of the neps leaves the machine unopened via
the flat stripping.
 Fig. 87 shows the approximate change in the number
of neps in the process.

8.  Improvement in the
disentangling of neps
 Reducing fiber density on
the cylinder by using larger
cylinder widths;
 Closer spacing between
the clothing surfaces;
 Sharper clothing;
 Optimal (not too low) licker-
in speeds;
 Low doffer speeds;
 Lower throughput.

9.  Elimination of short fibers.
 long fibers have more contact with the clothing of the
main cylinder than the short fibers. Thus longer fibers
are continually caught and carried along by the main
cylinder.
 Short fibers, on the other hand, offer less surface to
the clothing of the main cylinder; they therefore
remain caught in the flats clothing, are pressed into it
and leave the machine in the flat strippings.
 The card eliminates 1 - 2 % flat strippings.
Approximately half of the strippings are made up of
short fibers. The card therefore eliminates fewer than
1 % short fibers.

10.  Fiber short term blending.
 The card scarcely improves long-term blending, since
the time spent by the material in the machine is too
short.
 It improves transverse blending and fiber-to-fiber
blending because, apart from the OE spinner, the card
is the only machine to process individual fibers.
Intimate fiber-to-fiber mixing is achieved in the
formation of the web.
 Fiber orientation.(Partial Longitudinal )
 It is true that a parallel condition is achieved on the
main cylinder, but it disappears during formation of the
web between the cylinder and the doffer. Thus, the
card can be given the task of creating partial
longitudinal orientation of the fibers, but not that of

11. 5/12/2017
 Sliver formation.
 In order to be able to deposit the fiber material,
transport it and process it further, an appropriate
intermediate product must be formed. This is the
sliver.
 In extreme cases, card sliver has a count of 3 ktex
(new spinning processes) to 9 ktex.
 Generally the count lies between 4 and 7 ktex (for
direct feeding of draw frames up to 20 ktex) in the
short staple spinning mill.
 It also has to be kept in mind that all these
operations must be performed:
 • at very high output;
 • with very careful treatment of the fibers; and
 • very high utilization of the raw material.

12. (5) Operating principle (Imp)

13.  In modern installations, raw material is supplied via pipe
ducting (Fig. 88, 1) into the feed chute (of different designs)
(2) of the card. An evenly compressed batt of about 500 - 900
ktex is formed in the chute. A transport roller (3) forwards this
batt to the feed arrangement (4). This consists of a feed roller
and a feeder plate designed to push the sheet of fiber slowly
into the operating range of the licker-in (5) while maintaining
optimal clamping. The portion of the sheet projecting from the
feed roller must be combed through and opened into tufts by
the licker-in. These tufts are passed over grid equipment (6)
and transferred to the main cylinder (8). In moving past mote
knives, grids, carding segments (6), etc., the material loses
the majority of its impurities. Suction ducts (7) carry away the
waste. The tufts themselves are carried along with the main
cylinder and opened up into individual fibers between the
cylinder and the flats in the actual carding process. The flats
(10) comprise 80 - 116 individual carding bars combined into
a belt moving on an endless path. Nowadays some 30 - 46

14.  the rest are on the return run. During this return, a
cleaning unit (11) strips fibers, neps and foreign matter
from the bars. Fixed carding bars (9) and (12) are
designed to assist the operation of the card. Grids or
cover plates (13) enclose the underside of the main
cylinder. After the carding operation has been
completed, the main cylinder carries along the fibers
that are loose and lie parallel without hooks. However,
in this condition the fibers do not form a transportable
intermediate product. An additional cylinder, the doffer
(14), is required for this purpose. The doffer combines
the fibers into a web because of its substantially lower
peripheral speed relative to the main cylinder. A
stripping device (15) draws the web from the doffer.
After Calender rolls (16) have compressed the sliver to
some extent, the coiler (18) deposits it in cans (17). The

15. The operating zones of the card
 Material feed
 Requirements
 Irregularities in the sliver can be traced through into
the yarn, at least in the spinning of carded yarns;
that is, they diminish yarn quality.
 A fault-free sliver cannot be obtained unless the
feedstock is in an adequate condition, since every
irregularity in the feedstock is transmitted completely
into the sliver in an elongated form owing to the
draft.
 The time spent by the material in the machine is too
short for total compensation.

16.  Rule of Quality: In spinning, as in any other type of
manufacturing process, the rule must be that faults
should not be corrected and hidden but their
occurrence should be prevented from the start.
 Scutcher System:
 Where lap feed was used, this represented only a minor
problem, since the scutcher formed even laps, each of
which was checked for accuracy of count.
 Tuft Feed System:
 Tuft feed systems react much more sensitively. The tufts
must be transported pneumatically from a distributor unit
into the chutes of several cards. One of the cards is
always located very Close to the fan of the distributing
system, whereas the others are located at steadily
increasing distances from the fan. To obtain even feeding,
the batts in the individual feed chutes of all cards must be
equally thick, evenly distributed over the whole width of
the chute and of equal density.

17.  Requirements of high performance Cards
 An additional requirement for the feedstock of high
performance cards is a high degree of openness. This
very good openness in turn is the reason for the large
increase in performance of this card in comparison with
conventional machines.
 Higher loading of the clothing (600 to 900 k tex)
permits greater throughput of material. Correspondingly
finely opened material is therefore essential.

18. 11/12/2017 Basic concept of tuft feed
 A distinction must be made between two basic tuft feed
concepts:
 • one-piece chute without an opening system (Fig. 92);
 • two-piece chute with an opening system (Fig. 93).

19.  One piece Chute:
 In the one-piece chute, a column of material of a height
that is somewhat variable over time is pushed forward
toward the feed rollers. This form of chute is simple,
uncomplicated, economical and needs little
maintenance, but does not comply with the
requirements of a high-performance card.
 Two piece Chute:
 Two-piece chute is more complex and expensive, but
delivers a more even batt with better opened material.
 The upper half of the chute is a reserve chamber that
serves to receive the material from the blowroom and to
separate the material from the air.
 In the lower portion, after an opening stage at the
opening roller the quantity of material is held constant.
This material is lightly compressed by compressed air or
by vibrating plates in a continuous and even manner to

20. Open and Closed distribution system
 In open transport systems, the ducting terminates after
the last card. In closed systems, there is a circulation
path through which excess tufts, which have not been
taken up by any card, are returned to the distributor unit.
If too much material is present on the circulation path,
neps can be formed.
 Important Point:
 In all forms of pneumatic chute feed it is important that
when operation of a card ceases, all compression of
material in the chute is terminated, whether such
compression is effected by compressed air or by the
shaking of a vibrating plate. Otherwise, material
remaining in the chute will be over-compressed and
when operation restarts the resulting sliver will be too
heavy over a significant period.

21. The two-piece chute system
 Upper half of Chute:
 Raw material, delivered by a fan between the B 60
UNIflex and the chutes or by the A 78 UNIstore,
travels via the transport duct, which extends over all
integrated machines within a unit, into the reserve
chutes (upper half of the chute) of the individual cards.
 The transport air escapes via a perforated sheet and
is carried away by a suction duct.
 Regulation of feed:
 In this part of the chute (upper half) an electronic
pressure regulator ensures an approximately constant
height of material.

22.  Lower Half:
 The feed roller, which seals the upper half of the chute,
pushes the stock into the region of the opening roller,
and this roller in turn plucks out fi ne tufts and
discharges them into the actual feed chute (lower part).
 Here, controlled condensing is carried out by a metered
supply of compressed air from a fan.
 A perforated sheet that is part of the rear wall permits
the air to escape. It then flows back to the fan.

23.  An electronic pressure switch ensures constant
filling and density of material in the chute; this is
obtained by adjusting the speed of the feed roll
(above the opening roller).
 The airflow in the chute continually carries the
tufts to the zone in which the perforated sheet is
currently least covered by fibers. Even distribution
of tufts over the whole chute width is thus
obtained.

24. Fine cleaning integrated in the card chute
 With this solution, fine cleaning has been transferred to
the card chute. The existing opening position is
supplemented with a mote knife. The result is:
 • a card chute with integrated fine cleaning;
 • the high production load of the blowroom is now
distributed over several cards;
 • fine cleaning is performed very gently at considerably
lower production rates compared to the blowroom;
 • yarn quality is improved; for example, imperfections
(thick places, thin places and neps) are usually reduced
and short fiber content improves.

25.  Mode of operation (Fig. 94):
 1. Fiber tufts are fed uniformly to the card chute with
integrated fine cleaning.
 2. The fiber tufts are separated from the transport air in
the upper section of the card chute (1, 2) and form an
initial homogeneous batt.
 3. A feed roller with a feed trough (4) and a needled
cylinder (3) produces small tufts and thus a large tuft
surface.
 4. The integrated mote knife immediately eliminates the
exposed trash particles.
 5. The released tufts are blown into the lower section
(5) of the shaft by means of an additional controlled air
current and condensed there into a homogeneous batt.
 6. The perforated rear wall at this point permits
additional dedusting of the tufts.

26. Feed device to the licker-in
 Conventional system:
 A well designed feed device is expected to perform the
following tasks:
 • clamp the batt securely over its full width;
 • be able to hold the material back against the action of
the licker-in;
 • present the batt to the licker-in in such a manner that
opening can be carried out gently.
 The conventional feed assembly (Fig. 95) comprises a
stationary feed table with a feed plate (1) and a feed
roller (2) pressed against the plate. The feed plate is
formed as a special extension of the feed table and is
adapted to the curvature of the cylinder.

27.  The plate is formed at its upper edge with a nose-like
deflector (b, Fig. 96) to hold the batt. Facing the licker-
in, the plate has a fairly long guide surface (a).
 The deflector nose and guide surface have a significant
influence on quality and on the quantity of waste
eliminated. A sharp deflector nose gives good retention
of the fibers and hence an intensive, but unfortunately
not very gentle, opening effect. On the other hand, an
over-rounded curve results in poor retention and poor
opening. In this case, the licker-in often tears out whole
clumps of fibers. The length of the guide surface (Fig.
96 a) also influences waste elimination. If it is too short,
the fibers can escape the action of the licker-in.

28.  They are scraped off by the mote knives and are lost
in the waste receiver. If this surface is too long, it
presses the fibers into the clothing. This gives better
take-up of the fibers, but at the same time better
take-up of impurities. The result is a reduction in the
cleaning effect. The length of the guide surface is
dependent on the staple length, at least within a wide
range.
 The feed roller has a diameter of 80 - 100 mm and is
usually clothed with saw-tooth wire, the teeth being
directed against the flow of material. This gives good
retention of the batt, which ensures that the licker-in
does not tear whole lumps out of the batt. The
opening effect of the licker-in is thus more in the
nature of combing

29. Feed in the same direction as licker-in
rotation(unidirectional feed)

30.  The arrangement of the two feed devices is opposite to
that of the conventional system, i.e. feed roller (2) is
located below and plate (1) is pressed against the
roller by spring pressure.
 Owing to the rotation of the feed roller in the same
direction as the licker-in, the batt runs downward
without diversion directly into the teeth of the licker-in.
 The direction of rotation of the feed roller and the drum
is the same, the distance from the clamping zone (the
exit from the plate) to the feed roller/licker-in clamping
point (distance b/a) is adjustable.

31. The licker-in

32. 12/12/2017 The licker-in
 This is a cast roller with a diameter usually of around
250 mm.
 Saw-tooth clothing is applied to it.
 Beneath the licker-in there is an enclosure of grid
elements or carding segments;
 Above it is a protective casing of sheet metal.
 The purpose of the lickerin is to pluck finely opened
tufts out of the feed batt, lead them over the dirt-
eliminating parts under the roller and then deliver
them to the main cylinder.
 In high-performance cards, rotation speeds are in
the range of 800 - 2 000 rpm for cotton and about

33. The operation of the licker-in
 By far the greatest part of opening and cleaning is
performed by the licker-in.
 In machines with only one licker-in, opening is
performed to an extent where more than 50 % of al
fibers pass onto the surface of the main cylinder in the
form of tufts, and slightly less than 50 % in the form of
individual fibers. Treatment imparted by the licker-in is
therefore very intensive, but unfortunately not very
gentle.
 The licker-in combs through a fairly thick fiber fringe at a
rotation speed of 1 600 rpm (approximately 600 000 wire
points per second), a circumferential speed of around 21
m/sec (approximately 76 km/h) and a draft of more than
1 600.

34. The operation of the licker-in
 • the thickness of the batt;
 • the degree of openness of the raw material in
the feedstock;
 • the spacing between the operating devices;
 • the degree of orientation of the fibers in the
feedstock;
 • the aggressiveness of the clothing;
 • the rotation speed of the licker-in;
 • the material throughput.
 The type and intensity of the opening process
influences the final yarn, primarily as regards
neppiness, imperfections, evenness and strength.

35. Elimination of waste
 Waste elimination is very intensive and takes place
under the licker-in by means of special devices. The
classic cleaning assembly consisted of 1 - 2 mote
knives and a grid, one half of which was made of
slotted sheet and another half of perforated sheet.
 In this arrangement, elimination of foreign matter took
place exclusively by scraping off on the mote knives.
The grid sheets tend to serve as devices for guiding
and holding back fibers, i.e. they prevent additional
fiber losses that could arise from ejection.
 High-performance cards: the lickers-in of such cards
no longer operate with grids but with carding segments
(4, Fig. 99).
 In the last but one generation of the Rieter card, for
example, the tufts are first guided over a mote knife (2),
then over a carding plate (3), then again over a mote

36.  The carding plates are fitted with special clothing
(3a).

37.  A trash mote knife with suction unit is assigned to the
licker in.
 With the effective opening in the chute the C 60 card
with single licker-in provides much better opening than
the C 51.
 The single licker-in opens the material tufts even more
with absolutely minimal loss of sound fibers, and
extracts coarse trash and dust gently.

38. Transfer of fibers to the main cylinder
 Between licker-in and main cylinder the clothing is
configured for doffing. It follows that the opening effect
at this position cannot be very strong. Nevertheless, it
exerts an influence on sliver quality and also on the
improvement in the longitudinal orientation of the fibers
that occurs here.
 The effect depends on the ratio of the speeds of the
two devices. According to various investigations, this
ratio should be about 1:2; i.e., the draft between the
licker-in and the main cylinder should be slightly more
than 2 (this refers to a card with one licker-in, not to a
machine with several).
 The optimum ratio depends upon the raw material; in
any event, when speeds are to be altered, this

39. Auxiliary carding devices (carding aids)
Need for such assemblies
 The opening effect can now be represented only by
the number of points per fiber, i.e. average of total
fibers fed in per unit of time over the number of points
available in the same time. At the licker-in there may
be, for example, 0.3 points per fiber (three fibers per
point) and at the main cylinder perhaps 10 - 15 points
per fiber.
 If a given quality of yarn is required, a corresponding
degree of opening at the card is needed. However,
an increase in production at the card such as we
have experienced in recent years means quite simply
that more fibers must be passed through the
machine.

40.  In order to obtain the same carding effect (i.e. the same
number of points per fiber), the number of points per
unit of time must also be increased. This can be
achieved by:
 • more points per unit area (finer clothing);
 • higher roller and cylinder speeds;
 • more carding surface or carding positions;
 • finer opening of the fibers before feeding to the
cylinder.
 Little can now be done to increase the number of points,
since the mass of fiber also has to be accommodated
between the clothing: coarse fibers and a high
throughput demand coarser clothing; fine fibers and a

41.  Much has already been achieved by increasing speeds,
but further increases will prove steadily more difficult,
as an example will demonstrate.
 If, for example, the production of a card is increased
from 25 kg/h to 60 kg/h with the same number of points
per fiber, the main cylinder speed must be raised from
300 rpm to 750 rpm (according to P. Artzt).
 This cannot be achieved from either the design or the
technological standpoint. One effect, among many,
would be severe deterioration of the fibers.
 There remain only the third and fourth approach –
insertion of additional carding surface or additional
carding positions and/or installing more lickers-in. Here
also, there are two possibilities:
 • increase in the number of lickers-in;
 • fitting of additional carding plates.
Both have been put into practice.

42. Increase in the number of lickers-in
 Various card designs therefore now incorporate
multiple lickers-in, e.g. Rieter (Fig. 101),Trützschler
or Marzoli.
 They are optionally available. The clothing surfaces
are in the doffing configuration relative to each other,
and speeds must be increased in the through flow
direction, for example from 600 rpm (first licker-in) via
1 200 rpm to 1 800 rpm (third licker-in) (or the
velocity by increasing the diameter). Instead of grids,
the lickers-in are encapsulated in casings. Within
these casings there are a few small openings
including sharp-edged grid blades to scrap off the
impurities. The latter fall into a pipe and are sucked
away to the waste collecting devices.

43. Carding plates or carding bars

44. Carding plates or carding bars
 Today, carding aids can be applied at three positions:
 • under the licker-in;
 • between the licker-in and the flats;
 • between the flats and the doffer.
 These aids are in the form of carding plates or carding
bars. Carding plates have already been illustrated in
Fig. 99 at the licker-in, while carding bars are shown in
Fig. 102and Fig. 103. Plates are usually used in the
licker-in zone, while bars are being located increasingly
in the region of the main cylinder (Fig. 102 and Fig.
103).
 An aluminum carding profile (1) consists of 2 carding
bars (2).

45.  One of the advantages of bars is that they can be
provided in different finenesses, e.g. they can become
finer in the through-flow direction. Different
manufacturers use differing numbers of elements
(between one and four) per position. Special clothing is
required that must not be allowed to choke. Most
modern high-performance cards are already fitted with
these carding aids as integral equipment; all other
machines can be retrofitted by, for example, Graf of
Switzerland or Wolters of Germany.
 In use are also other carding devices of different design
and with different components, e.g. mote knives (4) with
guiding element (5) and suction tubes (3), etc.

46. Carding Bars at Infeed

47. Carding Segments at Delivery

48. Purpose and effect of carding elements
 If carding elements or additional lickers-in are not used,
the licker-in delivers mostly tufts, if not whole lumps, to
the main cylinder. These are compact and relatively
poorly distributed across the licker-in. If they pass into
the space between the cylinder and the flats in this form,
fiber-to-fiber separation becomes very difficult and
imposes considerable loading on the clothing. The
whole carding operation suffers.
 That is why high-performance cards presuppose
unconditionally individual fibers to be spread evenly over
the whole surface of the cylinder, and this again can be
obtained only by increasing the number of lickers-in and
the inclusion of carding elements, since they ensure
further opening, thinning out and primarily spreading out

51. Graph Analysis
 In the final analysis, these additional devices
reduce the loading on the carding zone
cylinder/flats, among other things. Two diagrams
(Fig. 104 and Fig. 105) by Schmolke and
Schneider [10] illustrate loading of the flats with
and without carding segments; in addition, it is
clear from these diagrams that the main opening
work is done at the first flats after entry of the
material.

52. 18/12/2017 Advantages of Carding Segments
 Carding segments bring the following advantages:
 improved dirt and dust elimination;
 • improved untangling of neps;
 • the possibility of a speed increase and hence a
production increase;
 • preservation of the clothing; and hence
 • longer life of the clothing, especially on the flats;
 • the possibility of using finer clothing;
 • better yarn quality;
 • less damage to the clothing;
 • cleaner clothing.

53.  Even carding elements following the flats exert a
considerable influence on yarn quality – although
the main carding work has been completed at that
stage. This is shown in a diagram by Artzt, Abt and
Maidel in Fig. 106 [11]. The segments create an
additional fine carding zone as the fibers rotate 5 to
10 times with the cylinder before they pass to the
doffer. This additional treatment of 5 to 10 times at
the segments also improves both fiber orientation
and transfer of fibers to the doffer.

55. Main cylinder
The cylinder
 The cylinder is usually manufactured from cast iron, but
is now sometimes made of steel. Most cylinders have a
diameter of 1 280 - 1 300 mm (Rieter C 60 card 814
mm, speed up to 900 rpm) and rotate at speeds
between 250 and 500 (to 600) rpm. The roundness
tolerance must be maintained within extremely tight
limits – the narrowest setting distance (between the
cylinder and the doffer) is only about 0.1 mm. The
cylinder is generally supported in roller bearings.
 The casing of the cylinder:
 Beneath the cylinder, and fully enclosing it, is a grid
made of sheet metal provided with transverse slots.
This is designed to remove impurities and maintain

56. Close Sheet Vs Grid
 since the cleaning effect is extremely small, some
manufacturers, such as Rieter, have replaced the grid
with a closed sheet metal casing. This enables the
multitude of small air vortexes that tend to arise at the
slots to be prevented.
 A closed sheet gives better fiber orientation on the
cylinder surface and often reduces the number of neps
at high cylinder speeds.
 Covering of the cylinder between the licker-in and the
flats, and between these and the doffer, takes the form
of protective casing. One of these protective sheets,
near the flats at the front of the machine, is specially
formed as a knife blade. The level and quality of the flat

57. Flats
Function
 Together with the cylinder (Fig. 107, 1), the flats
form the main carding zone. Here, the following
effects should be achieved:
 • opening of tufts into individual fibers;
 • elimination of remaining impurities;
 • elimination of some of the short fibers;
 • untangling neps (possibly their elimination);
 • dust removal (3);
 • high degree of longitudinal orientation of the
fibers.

58. Operation of Flats
 In order to fulfill all these requirements, a large continuous
carding surface is needed. The surface is created by a large
number of individual clothing strips secured to the bars of the
flats (2) and arranged in succession. 40 to 46 such strips are
commonly used (30 in Trützschler machines) to make up the
carding surface in the operating position.
 Elimination of Waste:
 Since elimination of waste can be carried out only by filling
the clothing, the flats must be cleaned continuously. They
must therefore be moved past a cleaning device (4) (hence
the name‘ revolving flat cards').
 Endless Path:
 The bars of the flats must be joined together to form an
endless, circulating belt, for which purpose they are fixed to
chains or toothed belts. In addition to the 40 - 46 flats (2)
(Rieter C 60 card: 27 flats) that interact with the cylinder (1),
further flats are needed for the return movement on the

60. Construction of the flats
 The bars of the flats are made of cast iron (nowadays
aluminum profiles, Fig. 109) and are somewhat longer
than the operating width of the card, since they rest on
adjustable (so called flexible) bends to the left and right
of the main cylinder and must slide on these guide
surfaces. Each bar is approximately 32 - 35 mm wide
(might change to smaller widths).
 The bars are given a ribbed form (T-shape) in order to
prevent longitudinal bending. A clothing strip (108 b) of
the same width is stretched over each bar and secured
by clamping, using clips (c) pushed onto the left- and
right-hand sides of the assembly. Since some space is
taken up by the upper edge of each clip, only a strip
about 22 mm wide remains for the clothing (hooks or
teeth). For this reason, the flats do not enable an

62. Securing of Flat bar to chain
 The bars are thickened at their left- and right-hand
ends in order to take fixing screws corresponding with
screw holes in the chains; the individual bars can thus
be secured to respective links of the circulating chains
(Fig. 110).

63. Heel and Toe Arrangement
 The slide surfaces on the bars are not ground level
but are slightly inclined (Fig. 111). Therefore, as the
flats move over the cylinder, they have a slight tilt,
i.e. viewed in the direction of material flow the
leading edge of each bar is spaced further from the
cylinder clothing than the trailing edge (1). The
result is that the fibers are not pushed along in front
of the flats, but can pass underneath them.

65. Movement of the flats
 The bars of the flats mesh individually, like an internally
toothed wheel, with the recesses in a sprocket gear,
and are carried along by rotation of the sprocket. The
ends of the bars of the operative flats slide over a
continuous bend with metal-to-metal friction.
 As the flats move at a very low speed compared with
that of the cylinder in principle, the flats can be moved
forward or backward, i.e. in the same direction as or in
opposition to the cylinder. If the flats move with the
cylinder (forward), the cylinder assists in driving the
flats and the removal of stripping is easier. Forward
movement therefore gives design advantages.
 Forward movement therefore gives design advantages.
On the other hand, reverse movement (against the

66. Movement of the flats
 In this system, the flats come into operative relationship
with the cylinder clothing on the doffer side. At this
stage, the flats are in a clean condition.
 They then move toward the licker-in and fill up during
this movement. Part of their receiving capacity is thus
lost, but sufficient remains for elimination of dirt, since
this step takes place where the material first enters the
flats.
 At that position, above the licker-in, the cylinder carries
the material to be cleaned into the flats. The latter take
up the dirt but do not transport it through the whole
machine as in the forward movement system; instead,
the dirt is immediately removed from the machine
(directly at the point where the flats leave the machine).

67.  A diagram by
Rieter (Fig. 112)
shows that the
greater part of
the dirt is flung
into the first flats
directly above
the licker-in.
 Rieter and
Trützschler
offer cards
with backward
movementof the

68. 19/12/2017 Carding plates instead of flats
 Hollingsworth company fitted four such plates above the
main cylinder where the flats would otherwise be
located. The plates were in the form of curved plates of
aluminum, provided with special steel wire clothing on
their internal surfaces. The plates were adjustable and
replaceable. This system has some striking advantages
but also very serious disadvantages. It is therefore no
longer available.

69. Cleaning positions in front of the flats
 Illustrated by the Rieter TREX system:
 The remaining impurities in the material on the cylinder,
and a large proportion of the dust, can be removed only
by way of total opening of the raw material, i.e. absolute
separation of the fibers.
 This degree of opening is achieved practically only once
in the spinning process, namely on the card cylinder
(similarly also in rotor spinning within the spinning unit).
This position is therefore ideal for the finest cleaning.
 For several years now, the manufacturers of cards have
used assemblies better suited to this purpose, e.g. the
Rieter company’s TREX system (Fig. 114). Beneath the
flats cover is a mote knife, set close to the cylinder; this
knife is associated with a suction tube. Foreign matter
stripped from the cylinder surface passes into the tube

70.  Nowadays it is
nearly standard to
have assemblies
comprising
carding plates and
mote knives
(behind each
other) above the
doffer.

71. Doffing
The doffer
 The cylinder is followed by
the doffer, which is designed
to take the individual fibers
from the cylinder and
condense them to a web.
The doffer is mostly formed
as a cast iron (or steel) drum
with a diameter of about 600
- 707 mm. (680 mm on Rieter
machines). It is fitted with
metallic clothing and runs at
speeds up to about 300
m/min.

72. The doffing operation
 It would appear logical to arrange the clothing of the
cylinder and doffer in the doffing configuration relative
to each other. In practice, however, they are actually
arranged in the carding configuration (Fig. 115).
 Carding Configuration:
 This clothing arrangement is essential because the
web that is finally delivered must be cohesive and
therefore the fibers must be interlaced with each other
and condensed.
 Disadvantage of Carding Configuration:
 One disadvantage is that the desired fiber
parallelization achieved on the main cylinder largely
disappears again, since a degree of random
orientation is necessary to form a web and to doff it.

73.  Another is the undesirable bending of the fiber ends
which occurs here, because the cylinder has to give up
the fibers to the doffer clothing, during which a certain
degree of sweeping through the fiber fleece takes place.
In the course of this step, the fibers are caught as hooks
on the points of the clothing. Accordingly
 • over 50 % of the fibers in the web exhibit trailing hooks
(at the rear end as viewed in the direction of material
flow);
 • about 15 % have leading hooks;
 • another 15 % have double hooks; and
 • only a small proportion are delivered without hook
deformation of any kind.
The doffing operation

74. The doffing operation
 A third disadvantage, namely the poor efficiency of
fiber transfer from the cylinder to the doffer, is in
practice more an advantage than a disadvantage.
 Of course, it is a fact that the fibers rotate with the
main cylinder about 5 to 10 (15) times (!) before
passing to the doffer, but it is also a fact that this
results in some important improvements:
 • it is an additional carding point;
 • the fiber-to-fiber blending effect increases, i.e.
 • a high degree of intermingling results there, which
is
 important, e.g. for man-made fiber/cotton blending);

75. Control of Transfer Factor
 As mentioned above, the result is a poor transfer
factor. However, certain provisions can influence the
latter positively, mainly by:
 • coordinating the clothing of both assemblies
accordingly;
 • the choice of a proper relationship of the peripheral
speeds;
 • providing for small distances between cylinder and
doffer.
 A reduction of the spacing between the two
assemblies, e.g. from 0.18 mm to 0.08 mm results, for
example, in a 100 % improvement in the transfer

76. 26/12/2017 Detaching
The detaching apparatus
 On old cards, a fly-comb (a rapidly oscillating comb)
oscillating at up to 2 500 strokes per minute takes the
web from the doffer. In modern high-performance cards,
a fly comb would be unable to perform this task because
the stroke rate would have to be significantly higher
(above the mechanical limit).
 A roller (Fig. 116, 1) now has the task of separating the
web from the doffer. In old cards, the web is guided into a
funnel, while being freely suspended over a distance of
30 - 50 cm and running together in a wedge shape.
 This arrangement is also no longer possible at the high
speeds of modern high-performance cards, since the
web would fall apart.

77.  Crushing rollers (web crushing)
 Between take-off roller (1) and transverse sliver
condenser (3), some manufacturers include two
smooth steel rollers, arranged one above the other
(Fig. 117). They can run without loading, in which case
they serve simply as guide rollers, or they can be
loaded with a pressure of about 15 N/cm and are thus
converted into crushing rollers.
 Now, the web must be condensed into a sliver while
still located within the detaching device. This can be
achieved in a number of ways; for example, with web
guide plates upstream from the detaching device, with
several transversely arranged guide rollers (Marzoli),
or with a transverse sliver condenser (3). In the latter,
either two counter-rotating belts carry the web into the
center or one circulating belt carries the web to one
side of the card.

78.  Where cotton with medium to high dirt content is being
processed, additional cleaning can be carried out here
by squashing the foreign particles (the fragments fall
away immediately after the rollers or in the subsequent
machines).
 Sticky cotton (honeydew) should also be carded
without crushing, as should cotton with a high
proportion of seed particles, because of the danger of
lap formation at the rollers (again sticky effect).
 With the high cleaning efficiency in high performance
cards this arrangement is out-dated.

79. Coiling in cans
 The sliver must be coiled in cans for storage and
transport.
 Can diameters now lie in the 600 to 1 200 mm range
and can heights are between 1 000 and 1 220 mm. If
the cans are supplied directly to the rotor spinning
machine, they must be smaller because less space is
available (better suited as round cans are rectangular
cans).
 The can diameter in this case is only about 350 to 400
mm. Fig. 118 gives Trützschler data on the capacity of
cans with a height of
1200 mm.
 Most manufacturers offer cards with can changers as
either standard equipment or an option. These permit
efficient operation since they enable the need for

80. Coiling in cans

81. 1/1/2018 Card clothing
Choice of clothing
 Of all the individual components of the card, the
clothing has the greatest influence on quality and
productivity. The development of new clothing
enabled, for example, the production rate of the card
to be increased from 5 kg/h to the current level of up
to 220 kg/h.
 New clothing was not, of course, the only factor
involved in this increase, but it made a major
contribution to it. Unfortunately, a price has to be paid
for this development in the form of a steadily
increasing departure from any possibility of universal
clothing, which was formerly aimed at.

82. Selection criteria
 Mills now have to make a difficult choice between
hundreds of available clothing types, a choice of the
utmost importance. Selection criteria are:
 • type and design of card;
 • rotation speed of the cylinder;
 • production rate;
 • material throughput;
 • raw material type (natural or man-made fibers);
 • fiber characteristics (mainly fineness, length, bulk, dirt
 content);
 • overall quality requirements;
 • price of the clothing;
 • service offered by the clothing supplier.
Operating conditions not only differ between mills – they
can alter
within a single mill. Compromises are therefore
unavoidable.

83. Classification
 Flexible clothing
 This features hooks of round or oval wire set into
elastic, multi-ply cloth backing. Each hook is bent into
a U-shape and is formed with a knee that flexes under
bending load and returns to its original position when
the load is removed. In short-staple spinning mills this
clothing is now found, if at all, only on the card flats
(Fig. 120).

84. Semi-rigid clothing
 In this, wires with square or round cross-sections and
sharp points are set in backing which is less elastic
than that of flexible clothing.
 This backing is a multi-ply structure with more plies
than the backing of flexible clothing, comprising layers
of both cloth and plastics.
 Flat wires are not formed with a knee, but round wires
may have one. The wires cannot bend and are set so
deeply in layers of cloth, and possibly foamed
material, that they are practically immovable.
 When subjected to bending loads, they are therefore
much less capable of yielding than flexible clothing
types. They are also found only on the flats (Fig. 121).

85. Semi-rigid clothing

86. Metallic clothing
 These are continuous, self-supporting, square wire
structures in which teeth are cut at the smallest
possible spacing by a process resembling a
punching operation. If the teeth are relatively large,
for example as in the licker-in, the clothing is referred
to as saw-tooth clothing.
 (The terms saw tooth clothing and metallic clothing
refer to the same thing.) Nowadays, the licker-in,
main cylinder and doffer use metallic clothing without
exception (Fig. 123).

89. Angle and other dimensions of metallic
clothing

90. (4) The most important operating
parameters of the clothing
 POINT DENSITY (NUMBER OF POINTS PER UNIT
SURFACEAREA)
 The point (or tip) density has a significant influence on
the carding operation. However, the number of points
and the speed of rotation of the cylinder must be
considered together.
 It is not simply the total number that is significant, but
also the number available per unit of time, i.e. the
product of the point density and the speed of
movement of the surface.
 Thus, low point populations can be partially
compensated by higher cylinder speeds. (This is not
always possible, since the overall result may be
deterioration in some quality parameters.)

91. Optimum Population
 In general, the higher the point population, the better
the carding effect – up to a certain optimum. Above
that optimum, the positive influence becomes a
negative one.
 This optimum is very dependent upon the material.
Coarse fibers need fewer points, as they need more
space in the card clothing;
 Finer fibers must be processed with more points,
since more fibers are present if the material throughput
is the same.
 Point density

92.  BASE WIDTH (a1)
 This influences the point density. The narrower the
base, the greater the number of turns that can be
wound on the cylinder and, correspondingly, the higher
the point population.
 HEIGHT OF THE CLOTHING (h1)
 The height of metallic clothing on the cylinder today
varies between 2 mm and 3.8 mm. The height must be
very uniform. It can also exert an influence on the
population, since shorter teeth – for a given tooth
carding angle – leave space for more teeth. Where
shorter teeth are used, the fibers are less able to
escape into the clothing during carding and better
carding over the total surface is obtained. Clothing with

93.  TOOTH PITCH (T)
 The population is also determined by the tip-to-tip spacing.
 CARDING ANGLE (a)
 This is the most important angle of the tooth:
 • the aggressiveness of the clothing; and
 • the hold on the fibers
 are determined by this parameter. The angle specifies the
inclination of the leading face of the tooth to the vertical.
 It is described as positive (a, Fig. 124), negative (b) or
neutral. The angle is neutral if the leading edge of the tooth
lies in the vertical (0°).
 Clothing with negative angles is used only in the licker-in,
when processing some man-made fibers. Since the fibers
are held less firmly by this form of tooth, they are transferred
more easily to the cylinder and the clothing is less inclined to
choke. Carding angles normally fall into the following ranges:

95.  THE TOOTH POINT
 Carding is performed at the tips of the teeth and the
formation of the point is therefore important (Fig. 125).
For optimum operating conditions the point should have
a surface or land (b) at its upper end rather than a
needle form. This land should be as small as possible.
To provide retaining power, the land should terminate in
a sharp edge (a) at the front.
 Unfortunately, during processing of material this edge
becomes steadily more rounded; the tooth point must
therefore be re-sharpened from time to time. Formation
of a burr at the edge (a) must be avoided during re-
sharpening. The tooth must only be ground down to a
given depth, otherwise land (b) becomes too large and
satisfactory carding is impossible – the clothing has to
be replaced.

96. THE TOOTH POINT

97. THE BASE OF THE TOOTH
 The base is broader than the point in order to give the
tooth adequate strength, and also to hold the individual
windings apart. Various forms can be distinguished
(Fig.126). In order to mount the wire, the normal profile
 ((a) for the licker-in,
 (b) for the cylinder) is either pressed into a groove milled
into the surface of the licker-in (a) or is simply wound
under high tension onto the plain cylindrical surface of
the main cylinder (b).
 (d) represents a locked wire and
 (c) a chained wire. Both can be applied to a smooth
surface on the licker-in; in this case a milled groove is no
longer necessary.

99. Tooth hardness
 In order to be able to process as much material
as possible with one clothing, the tooth point must
not wear away rapidly.
 Accordingly, a very hard point is needed, although
it cannot be too hard because otherwise it tends
to break off .
 On the other hand, to enable winding of the wire
on a round body, the base must remain flexible.
Each tooth therefore has to be hard at the tip and
soft at the base.
 A modern tooth has hardness structures as
shown in Fig. 127 (Graf).